Here is the full list of all 66 Alien Swarm achievements.
Kill 500 Swarm with deployable Sentry Guns.
Kill 250 Swarm with a Chainsaw.
Kill 250 Swarm with a Rail Rifle.
Kill 5 Swarm with explosive barrels in a single mission.
Kill 250 Swarm with a Minigun.
Kill 250 Swarm with a Grenade Launcher.
Complete a campaign on Normal difficulty or harder without any marines dying.
Kill 6 Swarm with a single Grenade.
Kill 250 Swarm with a Marksman Rifle.
Kill 100 Swarm with Incendiary Mines.
Kill 250 Swarm with a Shotgun.
Kill 100 Swarm with Laser Tripmines.
Deploy 10 ammo stashes that are used by other marines.
Kill 250 Swarm with a Vindicator.
Kill 5,000 Swarm.
Kill 250 Swarm with Twin Pistols.
Kill 250 Swarm with PDWs.
Complete Cargo Elevator within 2:50 on Normal difficulty or harder without any marines dying.
Complete Landing Bay within 1:25 on Normal difficulty or harder without any marines dying.
Complete a mission with no friendly fire incidents. Four marines must be present in the mission.
Kill 15 Swarm with all four marines under the effects of a Damage Amp in a single mission.
Awarded for finishing the Jacob campaign on Insane difficulty.
Freeze 6 Swarm with a single Freeze Grenade.
Kill 250 Swarm with the Assault Rifle.
Complete 10 wire hacks without access being logged.
Kill 250 Swarm with a Prototype Rifle.
Kill 250 Swarm with a Flamethrower.
Destroy all Swarm Eggs in a mission without allowing any to hatch.
Kill 100 Swarm with Hornet Barrages.
Kill 100 Swarm Grubs.
Kill 250 Swarm with a Tesla Cannon.
Stun 6 Swarm with a single Stun Grenade.
Unlock all the available weapons.
Complete the Jacob's Rest campaign on Hard difficulty or harder.
Complete a mission with better than 90% accuracy.
Kill 1,000 Swarm.
Complete the Jacob's Rest campaign on Easy difficulty or harder.
Complete the Jacob's Rest campaign on Normal difficulty or harder.
Heal all 4 marines with a single Heal Beacon.
Heal 300 points of damage in a single mission without dealing any non-melee damage to the Swarm.
Guard the squad's tech so that he takes no damage during the hack.
Seal a door with the welder.
Successfully perform a fast reload.
Kill 20 Swarm with melee attacks in a single mission.
Cure an Infested marine.
Kill 250 Swarm with an Autogun.
Kill a Swarm Parasite with a melee attack.
Roll under a Swarm Ranger projectile.
Kill a Swarm Boomer before it inflates.
Deliver the finishing blow to a Swarm Shieldbug.
Complete a mission on Normal difficulty or harder without any marines dying.
Complete 2 co-op missions online. Earns a Team Fortress 2 parasite hat.
Kill 25 drones without friendly fire. Four marines must be present in the mission.
Finish a mission without the tech getting killed.
Complete a mission on Normal difficulty or harder without receiving any damage.
Complete 10 computer hacks without access being logged.
Successfully perform 5 fast reloads in a row.
Kill 25,000 Swarm.
Kill 100,000 Swarm.
Complete Deima Surface Bridge within 2:30 on Normal difficulty or harder without any marines dying.
Complete Rydberg Reactor within 3:10 on Normal difficulty or harder without any marines dying.
Complete SynTek Residential within 2:30 on Normal difficulty or harder without any marines dying.
Complete Sewer Junction within 1:30 on Normal difficulty or harder without any marines dying.
Complete Timor Station within 4:25 on Normal difficulty or harder without any marines dying.
Awarded for finishing the Jacob campaign on Brutal difficulty.
Complete any mission on Brutal difficulty with Onslaught and Hardcore Friendly Fire enabled.